parsing,syntax analysis, or syntactic analysis is the process of analyzing a string of symbols,either in natural language ,computer language or data structures ,conforming to the rules of a formal grammar. The term parsing came from latin pars meaning parts of speech. within computational linguistics the term is used to refer to the formal analysis by a computer of a sentence or other string of words in to its constituents , resulting in a parse tree throwing their syntactic relation to each other,which may also contain semantic and other information.some parsing algorithms may generate a parse forest or a list of parse trees for a syntactically ambiguous input.
parsing a file means reading in a data stream of some sort and building an in memory model of the semantic content of that data. this aims at facilitating performing some kind of transformation on the data.
NASA thermodynamics file which is THERMO.dat file in which there are temperature range and 53 species are given in this data and each species contain 14 coefficients and temperture ranges and we have to parse these 14 coefficients to find specific heat ,entropy and enthalpy using formula as:-
it is the amount of heat per unit mass required to raise the temperature by one degree celsius. The relationship between heat and temperature change is usually expressed in the form shown below where c is the specific heat.
Entropy, measure of a system's thermal energy per unit temperature that is unavailable for doing useful works. Because work is obtained from ordered molecular motion,the amount of entropy is also a measure of the molecular disorder,or randomness,of a system.
Enthalpy ,a property of a thermodynamic system ,is equal to the system's internal energy plus the product of its pressure and volume.In a system contained so as to prevent mass transfer , for processes at constant pressure,the heat absorbed or released equals the change in enthalpy.
clear all
close all
clc
% Make directory
mkdir 'C:UsersAdminDesktopNASA File Parsing'
% Reading Data file - NASA Thermodynamic
% Open a file & 'r' Open the file for reading
f1=fopen('THERMO.dat','r')
gt=fgetl(f1);
% Obtaing Temperatures - by Reading Header Information
global_temp=fgetl(f1);
% Spliting
t=strsplit(global_temp);
% Converting string cells to numbers using str2num,
global_low_temp=str2num(t{2});
global_medium_temp=str2num(t{3});
global_high_temp=str2num(t{4});
% Temperature range & Gas Constant
% Temperature range assumed
Temp=linspace(global_low_temp,global_high_temp,1000);
%Universal Gas Constant J/(mol-K)
R = 8.314;
% skipping three comment lines in the file
for i = 1:3
gt=fgetl(f1);
end
for i = 1:53
gt=fgetl(f1);
A=strsplit(gt,'');
Species_SP=(A{1})
line_1=fgetl(f1) ;
a=strfind(line_1,'E');
%Extracting higher and lower temperature coefficients
% % Extracting FIRST 7 coefficients i.e HIGH-temperature coefficients
a1=line_1(1:a(1)+3);
a1=str2num(a1); %1
a2=line_1(a(1)+4:a(2)+3);
a2=str2num(a2) ; %2
a3=line_1(a(2)+4:a(3)+3);
a3=str2num(a3) ; %3
a4=line_1(a(3)+4:a(4)+3);
a4=str2num(a4) ; %4
a5=line_1(a(4)+4:a(5)+3);
a5=str2num(a5) ; %5
line_2=fgetl(f1);
b=strfind(line_1,'E');;
a6=line_2(1:b(1)+3);
a6=str2num(a6) ; %6
a7=line_2(a(1)+4:b(2)+3);
a7=str2num(a7); %7
%Extracting SECOND 7 coefficients - LOW-temperature coefficients
a8=line_2(b(2)+4:b(3)+3);
a8=str2num(a8); %8
a9=line_2(b(3)+4:b(4)+3);
a9=str2num(a9); %9
a10=line_2(b(4)+4:b(5)+3);
a10=str2num(a10); %10
line_3=fgetl(f1);
c=strfind(line_1,'E');
a11=line_3(1:c(1)+3);
a11=str2num(a11); %11
a12=line_3(c(1)+4:c(2)+3);
a12=str2num(a12); %12
a13=line_3(c(2)+4:c(3)+3);
a13=str2num(a13); %13
a14=line_3(c(3)+4:c(4)+3);
a14=str2num(a14); %14
% Specific heat calculation
Cp = Specificheat(a1,a2,a3,a4,a5,a8,a9,a10,a11,a12,Temp,R,global_medium_temp);
% Enthalpy calculation
H = Enthalpy(a1,a2,a3,a4,a5,a8,a9,a10,a11,a12,a13,Temp,R,global_medium_temp);
% Entropy calculation
S = Entropy_calc(a1,a2,a3,a4,a5,a8,a9,a10,a11,a12,a14,Temp,R,global_medium_temp);
% Calculating molecular weight of species
Molecularweight(i) = Molecular_weight(Species_SP);
% Read & write molecular list
Molecular_list = fopen('Molecular weight.txt','a+');
fprintf(Molecular_list, 'Molecular weight of %s is %d n',Species_SP,Molecularweight);
fclose(Molecular_list);
% plotting(CP,H,S,Temp,Species_SP)
% Saving as a folder
cur_dir=pwd;
mkdir(Species_SP);
cd(Species_SP);
% Plot 1, Specific heat (CP) vs Temperature Range (Temp)
figure(1)
plot(Temp,cp,'linewidth',2,'color','r');
xlabel('Temperature [K]');
ylabel('Specific Heat [kJ]');
title(sprintf('Varying specific heat with Temperature Range of %s',Species_SP))
grid on
saveas(figure(1),'Specific Heat.jpg');
%plot 3, Entropy (S) vs Temperature range (temp)
figure(3)
plot(Temp,S,'linewidth',2,'color','b');
xlabel('Temperature[K]');
ylabel('Entropy in [kj/(mol-K)]');
title(sprintf('Varying Entropy with Temperature Range of %s',Species_SP));
grid on
saveas(figure(3),'Entropy.jpg');
cd(cur_dir);
% Molecular weight
M = Molecular_weight(Species_SP)
f2 = fopen('molecular mass','w');
fprintf('%s n %s n %f n','species','Molecular mass',M)
fclose(f2)
end
MOLECULAR WEIGHT
% Molecular weight calculation function
function Molecularweight = Molecular_weight(Species_SP)
% Standard - atomic name
atomic_name = ['H','C','O','N','A'];
% Hydrogen, Carbon, Oxygen, Nitrogen, Argon
fprintf('Molecular Weight of');
fprintf(Species_SP);
fprintf(' : ');
% Standard Atomic Number
Atomic_Weight = [1.008 12.011 15.999 14.007 39.948];
% Starting Range of Molecule
Molecularweight = 0;
% adding atomic number to obtain particular value
for i = 1:length(Species_SP)
for j = 1:length(atomic_name)
if strcmpi(Species_SP(i),atomic_name(j))
Molecularweight = Molecularweight +Atomic_Weight(j);
position = j;
end
end
n = str2num(Species_SP(i));
if n>1
Molecularweight = Molecularweight + Atomic_Weight(position)*(n-1);
end
end
fprintf('molecular weight %s :',Species_SP);
fprintf('%d' ,Molecularweight);
disp('');
end
ENTHALPY CALCULATION
% Enthalpy Calculation function
function H = Enthalpy(a1,a2,a3,a4,a5,a6,a8,a9,a10,a11,a12,a13,Temp,R,lowtemp,midtemp,hightemp)
% comparing with global temperature
% if less than global temperature - minimum coefficients are taken
if Temp <= midtemp
H = R*Temp.*(a8 + ((a9*Temp)/2) + ((a10*(Temp).^2)/3) + ((a11*(Temp).^3)/4) + ((a12*(Temp).^4)/5) +((a13./Temp)));
else
% else maximum coefficients are taken
H = R*Temp.*(a1 + ((a2*Temp)/2) + ((a3*(Temp).^2)/3) + ((a4*(Temp).^3)/4) + ((a5*(Temp).^4)/5) + ((a6./Temp)));
end
end
ENTROPY CALCULATION
% entropy calculation function
function S = Entropy_calc(a1,a2,a3,a4,a5,a6,a8,a9,a10,a11,a12,a13,Temp,R,lowtemp,midtemp,hightemp)
% comparing with global temperature
% if less than global temperature - minimum coefficients are taken
if Temp <= midtemp
S = R.*(a8.*log(Temp) + (a9.*Temp) + a10*((Temp).^2)/2) + (a11*((Temp).^3)/3) + (a12*((Temp).^4)/4) + a14);
else
% Else- maximum coefficients are taken
S = R*(a1.*log(Temp) + (a2.*Temp) + (a3*((Temp).^2)/2) + (a4*((Temp).^3)/3) + (a5*((Temp).^4)/4) + a7);
end
end
SPECIFIC HEAT
% specific heat calculation function
function Cp = Specificheat(a1,a2,a3,a4,a5,a6,a7,a8,a9,a10,a11,a12,a13,Temp,R,lowtemp,midtemp,hightemp)
%comparing with global temperature
%if less than global temperature - minimum coeficients are taken
if Temp < midtemp
Cp = R*(a8 + (a9*Temp) + (a10*(Temp).^2) + (a11*(Temp).^3) + (a12*(Temp).^4));
else
Cp = R*(a1 + (a2*Temp) + (a3*(Temp).^2) + (a4*(Temp).^3) + (a5*(Temp).^4));
% Else maximum coefficients are taken
end
end
Code Explanation:-
1. clear all:- clear all the variables in the workspace
close all: closes all the plots and figures
clc : clears the command wndow
2. making a directory using 'mkdir" with location address
3. after that reading the text file "thermo.dat" file and opening it by using 'fopen' and 'r' as reading command.
4.for reading the line in a text file using 'fgetl'.
5.to obtain the temperature range from the thermo.dat file,using 'strsplit' to split the temperaure in to a particular string cell.
6.used 'str2num' for converting string cell to numbers.
7. devided the temperature in to a string and then converted to a number so that temperature values can be used seperately to solve the NASA thermodynamics.
8.using 'for&end' loops to skip the next three comment lines in the text file.
9.reading all the 53 species to plot the specific heat,enthalpy, entropy with temperature values and to find the molecular weights.
10.used 'for' loop to read 53 species.
11.used 'strfind' to find string.
12.using 'linspace' specified temperature from low to high.
13.adding universal gas constant 'R'.
14.Extracted higher and lower temperature coefficient by reading line by line from the species.
15.calling specific heat ,enthalpy,entropy function codes.
16. calculating molecular weight.
Syntax used during coding
fopen : open a file or obtain information about open files.
r : open the file for reading
fgetl: read the line from file.
strsplit: split string or character vector at specified delimiter.
str2num: convert a character array to numeric array.
strfind: find one string within another.
linspace: generate linearly spaced vector.
fprintf: write formatted data top file.
pwd: identify current directory.
mkdir: make new directory.
cd: change working directory.